<!DOCTYPE html>
<html>
<head>
    <meta charset='utf-8'/>
    <title>Add a generated icon to the map</title>
    <meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no'/>
    <script src='../assets/mapbox-gl-dev.js'></script>
    <link href='../assets/mapbox-gl.css' rel='stylesheet'/>
    <style>
        body {
            margin: 0;
            padding: 0;
        }

        #map {
            position: absolute;
            top: 0;
            bottom: 0;
            width: 100%;
        }
    </style>
</head>
<body>

<div id='map'></div>

<script>
    mapboxgl.accessToken = 'pk.eyJ1IjoibWFvcmV5IiwiYSI6ImNqNWhrenIwcDFvbXUyd3I2bTJxYzZ4em8ifQ.KHZIehQuWW9AsMaGtATdwA';

    var map = new mapboxgl.Map({
        container: 'map',
        style: 'mapbox://styles/mapbox/streets-v9'
    });

    map.on('load', function () {

        var width = 64; // The image will be 64 pixels square
        var height = 64; // The image will be 64 pixels square
        var bytesPerPixel = 4; // Each pixel is represented by 4 bytes: red, green, blue, and alpha.
        var data = new Uint8Array(width * height * bytesPerPixel);

        for (var x = 0; x < width; x++) {
            for (var y = 0; y < height; y++) {
                var offset = (y * width + x) * bytesPerPixel;
                data[offset] = y / width * 255; // red
                data[offset + 1] = x / width * 255; // green
                data[offset + 2] = 128;             // blue
                data[offset + 3] = 255;             // alpha
            }
        }

        map.addImage('gradient', {width: width, height: height, data: data});

        map.addLayer({
            "id": "points",
            "type": "symbol",
            "source": {
                "type": "geojson",
                "data": {
                    "type": "FeatureCollection",
                    "features": [{
                        "type": "Feature",
                        "geometry": {
                            "type": "Point",
                            "coordinates": [0, 0]
                        }
                    }]
                }
            },
            "layout": {
                "icon-image": "gradient"
            }
        });
    });

</script>

</body>
</html>